Reaction of Oncomelania hupensis to molluscicidal activity of the triterpene sapogenins from Nerium indicum

摘要

This paper has analyzed the reaction of O.hupensis to molluscicidal activity of the triterpene sapogenins from Nerium indicum . Five concentrations of the triterpene sapogenins from N.indicum (20, 40, 60, 80, 100 mg/L ) were used to treat O.hupensis , and 1 mg/L niclosamidum and dechlorided water were set as control. The result of probit analysis showed that the LD50 of triterpenoid saponing from N. indicum were: 78.31 mg/L after 2 days immersion, 30.26 mg/L after 3 days immersion, 20.50 mg/L after 4 days immersion, 14.19 mg/L after 5 days immersion . And the corresponding 95% confidence intervals were 63.60 – 108.19 , 9.49 – 44.42 , 2.86 – 30.90 , 0.23 – 22.79 mg/L, respectively. Based on the mortality of O.hupensis treated with triterpene sapogenins, variance analysis showed that the concentration and the time of treatment as well as their interaction had significant effect on the mortality of O.hupensis . The result of scanning electron microscope proved that 40 mg/L of the concentrations lixivium of the triterpene sapogenions from N.indicum caused apparent damage to the soft tissue of O.hupensis . Under transmission electron microscope, the changes to the liver and intestines structure of O-.hupensis were observed and documented. After 24 hour treatment the nuclear was swollen up; nucleolus decomposed; and nucleoplasm reduced. Rough endoplasmic reticulum (rER) was destroyed and vesiculated, and mitochomdrias in it were more than that in normal liver cell; After 48 hour treatment, the damage was more severe than ever, rER were almost destroyed and became many small saccules, some of nucleus and mitochondrias ruptured; In the first 24 hours, the microvilli arrange of intestines was out of order, and some was fallen, and the area around intestines was swelling; after 48 hours, the microvilli arrangment became significantly out of order, and a lot were fallen. The area around intestines was swelling deeply, lots of vacuoles could be seen, and some nucleolus was dissociated, c.Cell organ in cytoplast had vacuole of different sizes, and its configuration was very difficult to be distinguished, c.Cell membrane was imperfect, there was serious damnification. The esterase (EST) isozyme electrophoresis in liver of O. hupensis was analysed.. The activity of enzyme was higher than control group after been treated for 24–48 h and the activity of enzyme was lowered and disappeared after 72 h. We have obtained ultrastrure evidence in killing snails in the microscopic field for the morphologic pathology of O. hupensis caused by allelopathy. This result has provided the foundation for constructing plant community with strong allelopathy to kill O.hupensis [ Acta Zoologica Sinica 54(3): 489–499, 2008].